1. Field of the Invention
The present invention generally relates to devices for testing semiconductor wafers during manufacturing and, more specifically, to testing devices which do not contact the device under test (DUT).
2. Description of the Related Art
During the manufacturing of semiconductor devices and wafers, unwanted defects occasionally occur. In order to reduce such defects and increase production yield it is desirable to test the item being manufactured at various points during the manufacturing process.
Conventional systems remove the item being manufactured from the production line at different fabrication steps and test the item for defects. Depending on the development needs, a semiconductor wafers could be pulled at the post-silicide polysilicon stage, during the local interconnect stage or at several of the metalization stages, such as post metal-1 anneal, post via-1 planarization, or post metal-2 etch, for testing.
Conventional testing systems come in physical contact with the item being manufactured. Specifically, most conventional systems connect test pins to contacts on the wafer being manufactured to determine whether the electrical connections formed on the wafer are operating properly.
Some conventional devices measure the electromagnetic near field distribution adjacent to the device under test. Such systems require a physical connection to supply power to the device under test.
By making physical contact with the item being manufactured, the conventional systems introduce foreign materials in the production line, which increases the chance of defects being produced in subsequent processing steps and, therefore, reduces overall yield for the manufacturing process.